TPS54122-Q1: SW waveform at light load

Given Ding

Genius 10145 points

Part Number: TPS54122-Q1

Hi,

just want to check on below questions:

we found SW waveform as below at light load, does it means the HS FET body diode works but why does it works?

over 6 years ago

0 JohnTucker over 6 years ago

TI__Guru**** 191445 points

Given,

The TPS54122-Q1 is sinking current when the low side switch turns off. During the dead time it will flow back to the input thru the high side body diode which clamps the SW node to one diode drop above VIN.

0 Given Ding over 6 years ago in reply to JohnTucker

TI__Genius 10145 points

Hi John,

Thanks.

From the waveform the deadtime is >20ns which seems a little long which affect the light load eff, so the deadtime is fixed to guarantee the reliability at whole load , right ?

one more question, for start up, we found below waveform, could you please kindly check?